Modelling of wind tunnel interference on helicopter measurements and assessment of the currently used corrections based on the HeliNoVi database

Riziotis, VA; Voutsinas, SG

dc.contributor.author	Riziotis, VA	en
dc.contributor.author	Voutsinas, SG	en
dc.date.accessioned	2014-03-01T02:51:08Z
dc.date.available	2014-03-01T02:51:08Z
dc.date.issued	2007	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/35386
dc.relation.uri	http://www.scopus.com/inward/record.url?eid=2-s2.0-34547588639&partnerID=40&md5=c1876d1c2e182fea5d1fef6ba4b76ffd	en
dc.subject	Aeroelastic modelling of helicopters	en
dc.subject	HeliNoVi	en
dc.subject	Open jet wind tunnel interference	en
dc.subject	Vibration analysis	en
dc.subject	Vortex methods	en
dc.subject.other	Computer simulation	en
dc.subject.other	Helicopters	en
dc.subject.other	Mathematical models	en
dc.subject.other	Measurement theory	en
dc.subject.other	Aeroelastic modeling of helicopters	en
dc.subject.other	Open jet wind tunnel interference	en
dc.subject.other	Wind tunnels	en
dc.title	Modelling of wind tunnel interference on helicopter measurements and assessment of the currently used corrections based on the HeliNoVi database	en
heal.type	conferenceItem	en
heal.publicationDate	2007	en
heal.abstract	Wind tunnel tests on scaled helicopter models in combination with advanced numerical simulations constitute the two powerful tools of modern applied rotorcraft research. In spite of the substantial progress made on both over the last years, there are still some open issues. Wind tunnel tests are subjected to scale and tunnel interference effects while simulation models still require validation which is usually carried with reference to tunnel measurements. To this end, tunnel interference is taken into account by correcting the pitch attitude on the basis of the Glauert's and Brooks' correction methodologies. With the aim of clarifying this point, within the HeliNoVi European research project, a simulation model which also includes the tunnel interference was developed and simulations were carried out. The core model is GenUVP, a new aeroelastic code based on vortex theory which allows simulating the development of the tunnel shear layer. The model combines panel methods with vortex blob approximations for the free vorticity which is extended to the shear layer of the tunnel. The simulations are carried out in time on the full configuration demanding at every time step convergence of the non-linear aeroelastic coupling equations. In addition load trim is applied. Simulations of this type especially when the evolution of the tunnel shear layer is included require a large number of full revolutions in order to attain convergence to a periodic solution. In order to make simulations feasible, special time saving techniques are introduced in the wake. Following a similar experimental exercise, free flight results are compared with results obtained in the wind tunnel with and without correcting the angle of attack in terms of the rotor power. It follows that the correction needed closely follows the results of the experimental exercise at all speeds. Furthermore by correcting the angle of attack close correlation of the vibratory loads between free-flight conditions and operation inside the wind tunnel is confirmed. The first part of the conclusions drawn, confirms the consistency of the tunnel interference modelling while the second part reconfirms the need for reviewing and fine tuning the structural data for the particular model. Other worth noticing capabilities of the model, are the possibility of defining the best positioning of the model and of also correcting the roll angle.	en
heal.journalName	National Aerospace Laboratory NLR - 32nd European Rotorcraft Forum, ERF 2006	en
dc.identifier.volume	1	en
dc.identifier.spage	408	en
dc.identifier.epage	427	en